Brake pipe leakage compensator



Oct. 24, 1933. u A, wHlTAKER 1,932,058

BRAKE PIPE LEAKAGE COMPENSATOR Filed Dec. 27. 1929 III/11111111 INVENTOR UNCAS A.WH|TAK E R ATTO NEY Patented ctl 24, 1933 i f I v BRAKE PIPE LEAKAGE COMPENSATOR Uncas A. Whitaker, Canton, Ohio, assign'or to The i/Vestinghouse Air Brake Company, Wilmerding, Pa, a corporation of Pennsylvania Application December 27, I929 Serial No. 416,823

flSClaims. 1 (01. 303-18) This invention relates to fluid pressure brakes, merit view of the rotary valve and seat of; the and more particularly to an automatic train conbrake valve device shown in Fig.1. trol apparatus in which the brakes are applied As shown in the drawing, the automatictrain byreducing the brake pipepressure in successive control equipment comprises a brake valve destages. I 1 vice 1, a splitreduction valve device 2, a mag,

Various means have heretofore been disclosed net valve device 3, and two feed valve devices 4 .for applying-the brakes on a train by reducing, and 5. v the brake pipe pressure in successive stages, such The brake valve device 1 comprises a casing means, for example, being shown in Patent No. having a valve chamber- 6 containing a rotary 1,663,736, granted March 27, 1928, to Thomas slide valve 7 adapted to be operated by a handle Thomas and Earle :3. Cook. I 8 and casing also contains the usual equalizelccording to the above mentioned patent, an ing discharge valve mechanism comprising a pisinitial light reduction is effected in brake pipe tone and a brake pipe dischargevalve 10 adapt pressure to lightly apply the brakes, and then. ed to be operated lay-said piston. A chamber 11 5 after a time, sufilcient to bunch the slack in the atone side of the piston 9 is connected through train, a second and heavier reduction is effected a passage and pipe 12 to the usual equalizing res: in brake pipe pressure to produce the desired apervoir and a chamber 14 at th other side of plication of the brakes. said piston is connected through passage 15 to According to the above mentioned patent, the the usual brake pipe 16. 1 time from the start of the first to the start of the Preferably associated-with the brake valve deecohd reduction in brake pipe pressure is govvice is a brake pipe charging control valve de- Led by the time the equalizing piston in the vice comprising two spaced diaphragms 17 and valve device holds the brake pipe discharge 18, having their outer edges secured in the case aive open eiiecting the initial reduction. and a slide valve'l9 contained in a chamber Leakage from the brake pipe ai ds the brake pipe 20 intermediate said diaphragins, which chamber discharge valve in reducing the brake pipe pres is open to a reservoir 113 through passage and su a'and under such a condition, the discharge ipe 114. The slide vaivell is interposed between valve close sooner than if the brake pipe is two shoulders'forrned by the members 21 which leak proof, with the result that the second stage connect said diaphragins toget er, and is therev of reduction will be started sooner'than it should by adapted to-be operated by said diaphragrns. be and cause vere running in of the slack, Said slide valve is provided on the upper edge which might result in damage to the train. with serrations or saw-like teeth 22, which un- One object of my invention is'to provide means der certain conditions are adapted to be engaged for ensuring the proper, and a substantially conby corresponding saw teeth 23 on aplunger mem-' stant, elapse of time between the first stage and" her 24;

the sec stage in a brake, pipe reduction, vir- The plunger member 2% is provided with a stem respecti e of degree of brake pipe leakage, for 25 operatively mounted in a suitable bore in the atrain of a certain length." l I casing and having formed at one end a flange 26.

Another and more-specific object of my inven- Secured between said flange and a follower 27,.by tion is to ovide means, operative during the irimeans of a nut .28 having. screw-threaded enitial stage or" a two-stage reduction in brake pipe gagement on the stern, is'a piston 29, preferably pressure, to automatically comp nsate for leakin the form of a flexible cupped packing slidably from the ake pipe, so as to provide a submounted in a bore in the casing. The piston 29 stantially cons; nt'tirne intervalbetween the first has at one side a chamber 30 and at the opposecond stages of a two-stage'reduc'tion in site. side a chamber31, a spring 32 being conbrake pipe pressure on a train of certain length, tained in chamber 31 and acting on flange 26 to irrespective of the degree of brake pipe leakage on urge the piston to the position shown in the drawsaid. train. I 1 g, V

Other objects advantages will appear The diaphragm 17 has at its outer face a chamso the following more detailed description of my inher 33, and diaphragrni has at its outer face a vention. chamber 34, a spring 35 being contained in cham 1 nying drawing; Fig. 1 is a diaber 34 to urge the diaphragms and slide valve 19 innatic View, partly in section, ofan autoto the left; i V

train control equipmentembodying my in-' Preferably associatedwith the brake valve devention; and Fe. 2 a diagrammatiedevelopviceis anapplication valvede vice comprising a 11 0 piston 36 having at one side a chamber 3'7, and a slide valve 38 contained in a chamber 39 and adapted to be operated by said piston. A spring 40 in chamber 3'7 is provided to normally maintain said piston and slide valve in the position shown in the drawing.

The split reduction valve device 2 is of substantially the same construction as disclosed in the h reinbefore mentioned patent and comprises a control portion and a hold-back portion.

The control portion of the split reduction valve device comprises a casing containing differential pistons ll and 42, said pistons being connected by a stem 4.3 and being adapted to operate a slide valve a l contained in a valve chamber formed intermediate said pistons. The piston 41 has at one side a chamber l6 connected to the seat of the brake pipe discharge valve 10 through passage and pipe 4'7, and the piston 42 has a chamber 48 at the opposite side, which chamber is in constant communication with the brake pipe 16 through a passage 49.

The hold-back portion of the split reduction valve device comprises a casing containing a piston 50 having at one side a chamber 51, and a slide valve 52 contained in a chamber 53 and adapted to be operated by said piston. A spring 54 is provided in chamber 53 to urge piston 56 and slide valve 52 to their normal position, as shown in the drawing.

The magnet valve device 3 comprises a 55 and double beat valves 56 and 5'7 adapted to be controlled by said magnet. The magnet is adapted to be controlled according to trafiic conitions, and when favorable, the magnet is energized. When the trahic conditions are unfavorable, the magnet is deenergized.

In operation, when the traihc conditions are favorable, the energization of magnet 55 operates to seat valve 56 against the pressure of a spring 58.

Fluid under pressure is supplied from a main reservoir 59 through pipe 60 to the feed valve d vice 4 and from said pipe through passage 61 in the brake valve device to the rotary valve chamher 6 and to the application slide valve chamber 39. From said valve chamber, fluid under pressure flows through a port 62 in the application piston. 36 to chamber 3'7 and from thence through passage and pipe 63 to a chamber 64 in the magnet valve device 3. The valve 56 being seated, however, the pressure of fluid in chamber 64 and application piston chamber 3'7 builds up equal to the pressur of fluid in the application valve chamber 39.- With the fluid pressures on the opposit sides of the application piston 38 thus balanced, the spring 40 maintains the piston 36 and slide valve 38 in their normal release position, as shown in the drawing.

The feed valve device 4 is adapted to reduce the pressure of fluid supplied from the main re ervoir 59 through pipe 60, and supply fluid at the reduced pressure to pipe and passage 66 connected to the seat of the rotary valve '7.

With the brake valve device in the usual running position, fiuid at the reduced pressure supplied by the feed valve device 4 is permitted to flow through port 67 in the rotary valve '7 to passage 68, which is connected to slide valve chamber 20 of the brake pipe charging control valve device, and to the seat of the application slide valve 38.

With the application slide valve in release position, fluid at feed valve pressure is permitted to flow from passage 68 through cavity 69 in said slide valve to passage is and from thence to diatime as the brake pipe is charged.

phragm chamber 33. The fluid pressures in diaphragm chamber 33 and valve chamber 20 are thus balanced. Diaphragm chamber 34 is connected through passages '71 and 15 to brake pipe 16 which is initially at atmospheric pressure. Thus, the pressure of fluid in valve chamber 29 is permitted to deflect diaphragm 18 to the right, which compresses spring 35 and pulls slide valve 19 to a brake pipe charging position.

In charging position of slide valve 19, a passage '72 is uncovered in seat, fluid under pressure supplied by 1" eed valve device 4 to valve chamber 20, in the manner hereinbefore described, is permitted to flow through the passage '72 and passage 15 to the bralie pipe 16, thereby charging said brake pipe.

Fluid under pressure also flows from passage '72 through passage 15 to chamber .4 at the lower side of the equalizing discharge valve piston and from 15 through a port.'73 in the rotary valve '2 to a passage 74, and from thence through a cavity '75 in the application slide valve and passage 12 to piston chamber 11 and equalizing reservoir 13, thereby charging the chambers i l and ii and said reservoir with fluid at brake pipe pressure. The fluid pressures being equal on opposite sides of the piston 9, said piston .cd to normally maintain the brake pipe e valve in the usual manner. n chamber as, being connected to g oassages '71 and 15, is also charged with iluid under pressure at the same When the pressure of iiuid in diaphragm chamber 34 plus the presume of spring 35 becomes sli htly greater than tl-e opposin pressure of nuid in diaphragm chamber 38, the is operated to shift the slide valve 19 to the left and lap brake pipe supply passage 2, so as to prevent flow of under pres ure through passage to the brake pipe. Assuming the brake pipe 16 to be free from leakage, the fluid under pressure remains bottled up therein until intentionally vented, and until such ventim occurs, the slide valve 19 remains in the lapped position, just described.

It will be noted that in order. to shift the slide valve 19 to lap position, the pres .re of fluid supplied by the feed valve device 4 to diaphragm chamber 33 is overcome by the slightly higher comb-ned pressures of spring and fluid at bra" e pressure in chamber It obvious, therefore, that the fluid pressure in chamber 34 is less than the fluid press-re in chamber oy an amount slightly less th pressure of spring further thatt' ed valve device a is adjusted at a higher pre sure than that'carried in the brake pipe 16, for reasons to be fully de scribed hereinafter.

With the brake pipe discharge valve 1 seated, the control piston chamber 45 of the split reduction valve device is connected to the atmosphere through passage pipe 4'? and choke plug '77 in the brake valve device. The control p ston cham ber being charged. with fluid under pressure from brake pipe 16 through sure or" fluid acting on piston 42 maintains pistons s2 and ll, and slide valve in the normal posi-- tion shown in the drawing. I V

In the normal position of the control slide valve 44, the valve chamber as is open to the iosphere through port '78 in saidslide valve, passage '79, which also connects with a reservoir 80, past check valve 83., through passage and pipe 82. cavity 83 in the application ide valve 38 an-:.

so 49, the prev from thence through atmospheric passage 84. The locking piston chamber 30 of the brake pipe charging valve device is also normally atatrnospheric pressure due to the connection through a I restricted atmospheric port 85, as well as through piston in the position shown in. the drawii'igiin passage and pipe 86,-cavity 87 in the control slide valve 44 and atmospheric, passage 88, With the locking piston chamber thus at atmospheric pressure, the pressure of spring 32 maintains said which position saw teeth 23 on plunger 24 are held out of engagementwith saw teeth 22 on slide valve 19.

In the normal position of the control slide valve, the holdback piston chamber 51 is open to the atmosphere through passage 89, cavity 90 in the control slide valve 44 and atmospheric passage 91, which permits spring: 54-t0 maintain the piston and .slide valve 52 .in the position shown in thedrawing, in Whicha timing reservoir 92 is connected to the atmosphere through pipe and passage 93, valve chamber 53 and atmospheric port 94. y A first reduction reservoir 95 is normally open 1 to the atmospherethrough pipe and passage 96,

valve and passage and pipe 106.

When the trafiic conditions become unfavouable the magnet 55 is deenergized. Spring 58 then unseats valve 56, which permits fluid-' under pressure to be vented from the application piston chamberB'? tothe atmosphere through passage and pipe 63, chamber 64 in the magnet valve device 3, past unseated valve- 56 and'through atmospheric passage 19'1- Upon venting of the fluid under pressure from piston chamber 37,

the application piston 36 andslide valve 38 are shifted to application position by the pressureot fluid in valve chamber 39, in which position said piston engages a gasket 108.

In application position of the application'slide valve, the equalizing piston chamber 11- and equalizing reservoir 13 are connected to the first reduction reservoir 95 through-passage 12,cavity 5 in the application slide valve and passageand pipe 96. Fluid under pressure is thus permitted to flow from said piston chamberandreservoir and reduce the pressurein chamber llacting on the piston 9. Fluid at brake pipe pressure acting injpiston chamber 14 then shifts the piston '9 upwardly, which unseats the brake pipe dis charge valve 10.

With the brake pipe discharge Valve unseated,

fluid under pressure is permitted to flow from the,

brake pipe 16 throughpassage15 to passage 47, through which it flows to a choke plug 77 and to control piston chambered of the. split reduction valve device. The chokeplug 7'7 restricts the flow from passage 4}? to the atmosphere; so as to en surea buildup of pressure'in piston chamberl'efi;

but the-restricted flow to the atmospherereduces sage 4'7-to the control piston chamber e6 acts on piston lland-since said piston is of larger area than piston 42, which is subject directly to brake pipe, pressure, the piston iloperates to shift the. piston 42 and slidevalve 44 downwardly to first reduction position.

In, first reduction position of valvev l i, the holdebaok piston chamberEl is con-. nected through passage 89, cavity infthe controi slide valve and a passage and pipe 108-to the feed valve device5, which is-adapted .to reduce the pressure of fluid supplied from anyjsuitable source and supply fluid at such reduced pressure to pipe 108 from whence it is permitted to flow to the hold back piston chamber 51. The pressure of fluid thus supplied to piston chamber 51 shifts the hold-backjpiston 50 and slide valve 52 to first reduction position, in which passage 96 from the first reduction reservoir is disconnected from passage 101 from the second reduction reservoir 99. l

Withthe two reduction reservoirs disconnected from each other, the pressure of fluid in the equalizing-reservoir. 13 is permitted to equalize into the firstreduction reservoir only, thereby limiting the degreeoi reduction in the equalizing piston cham- 11 to a predetermined amount, which, as a result, limits the degree of brake pipe reduction to a corresponding amount, as Will'be more fully explained hereinafter.

. 'With the hold-back slide valve 52 in the first rsduction position, passage 93 is lapped and fluid at the pressure supplied to the] hold-back piston.

chamber 51 through passage 89 is also permitted to flow from said passage through a restricted port 109 to passage 93 and timing reservoir 92, which is thereby permitted, to charge with fluid under pressure at a predetermined rate. v

vIn application position of the application slide. valve 38 and first reduction position of the control slide valve 44, fluid under pressure is permitted to flow. from-brake pipe 16 through pas-=; sages 15 and 110;i n thebrake valve device, cavity 83 in slide valve-38, passage and pipe 82, cavity 111 in the control slide valve and passage 79 to the lock-up reservoir 80, and thereby charge" said reservoir.. V x

As hereinbefore described, the pressure in equale izing piston chamber ll is reduced apredetermined amount by equilization of the pressures in the equalizing reservoir 13 and first reduction re'sc ervoir95. When the brake pipe pressure in piston chamber 14 is reduced, by flow to the atmosphere through the exhaust choke plug 'Z'Lto a degree slightly less than the reduced pressure in piston chamber 11, the equalizing pistonis operated to seat the brake pipe discharge valve 10, so as to prevent further discharge of fluid under pressure from the brake pipe; I

' After the brake pipe discharge valve seats, fiuid under pressurefiovv's "from the pipe pressurein control piston chamber 48 to shift the control pistons l2 and 41 and slide valve 44 upwardly to their normal position, as shown in the drawing.

In the normal position of the control slide valve,

fluid under pressure is permitted to flow from the hold-back piston chamber 51 and the timing res ervoir 92 through passage cavity earn the control slide valve and to the atmosphere through passage91; -When' the pressure in chamber 5 1 is 3.}.

the control slide control piston chamber 16 to the atmosphere and permits brake thus reduced to a predetermined degree, spring 54 shifts piston and slide valve 52 to their normal position as shown in the drawing, in which position the first reduction reservoir 95 is connected to the second reduction reservoir 99 through pipe and passage 96, cavity 100 in slide valve 52, and passage and pipe 101. Fluid under pressure is thereby permitted to flow from the first reduction reservoir 95 and equalizing reservoir 13 to the second reduction reservoir 99 and effect a second reduction in pressure in equalizing piston chamber 11. The equalizing piston 9 is then operated in the same manner as hereinbefore described to effect a corresponding second reduction in brake pipe pressure.

It will here be noted that the time elapse from the start of the first reduction to the start of the second reduction is governed by the interval of time the brake pipe discharge valve 10 is unseated, during which time the timing reservoir 92 is being charged, plus the time for the pressure of fluid in said reservoir to be reduced after the first reduction is completed.

When the control slide valve 44 is moved to its normal position, after the first reduction in brake pipe pressure is completed, fluid under pressure is permitted to flow from the lock-up reservoir through passage 79 and port '78 to the control valve chamber 45, wherein it is bottled up and acts on piston 41 to prevent the pressure of fluid supplied to piston chamber 46 during the second reduction in brake pipe pressure from shifting the control pistons 41 and 42 and slide valve 44 to first reduction position again, which would prevent the second reduction from being effected.

When the application slide valve 38 is moved iton 29 shifts the plunger 24 downwardly, causing teeth 23 to engage teeth 22 on slide valve 19, and lock said slide valve in the position it was in prior to deenergization of the magnet 55. In the operation hereinbefore described, it was assumed that the brake pipe 16 was leak proof and that after the brake pipe was charged with fluid under pressure, the slide valve 19 was shifted to lap the passage 72, so, as a result, in the case of a leak proof brake pipe, said slide valve is locked in lap position during the first reduction.

The locking piston chamber 30 is connected to' the control slide valve 44 through passage and pipe 86, which is lapped by said slide valve in first reduction position, but upon return of said slide valve to normal position at the start of the second reduction, said passage is opened to the atmosphere through cavity 87 and atmospheric passage 88. This permits fluid under pressure to be vented from the locking piston chamber 30 and reservoir 104 at the start of the second reduction.

Venting of the fluid under pressure from looking piston chamber 30 permits spring 32 to operate said piston and plunger 24 so as to disengage teeth 23 from teeth 22 on slide valve 19. The diaphragm chamber 33 being open to the atmosphere, the fluid at brake pipe pressure in diaphragm chamber 34 is then permitted to maintain said slide valve in lap position.

ation of the apparatus in the case of a leak-proof brake pipe such as was assumed to be the condition of brake pipe 16 in the preceding description of operation. However, if there is leakage from the brake pipe to the atmosphere, the brake 'pipe charging valve device operates in a manner different from that her'einbefore described, to render the brake pipe leakageineifective during the first reduction in brake pipe pressure as will now be explained.

Assuming that there is leakage from the brake pipe 16, such leakage tends to reduce the pressure of fluid in the brake pipe and in diaphragm chamber 34 of the brake pipe charging valve device, which chamber is connected tothe brake pipe through passages 71 and 15. With the brake equipment in the released condition, as hereinbefore described, the pressure of fluid in diaphragm chamber 33 is governed by the adjustment of the feed valve device 4 and therefore is substantially constant.

Leakage from the brake pipe to the atmosphere, reducing the pressure in diaghram chamber 34, permits the pressure in diaphragm chamber 33 to deflect the diaphragms 17 and 18 and shift slide valve 19, so as to partially; uncover passage '72. This permits fluid under pressure to flow to the brake pipe and diaphragm chamber 34 and tends to maintain the pressure therein against the leakage. The construction of the brake pipe charging valve device is such, however, that the degree of opening through passage 72, as governed by the slide valve, permits an amount of fluid under pressure to flow to the brake pipe substantially equal to the amount lost therefrom by leakage, and in such a position of the slide valve 19, the opposing pressures acting on the diaphragms 17 and 18 are balanced thereby placing the brake pipe charging valve device in a state of equilibrium.

It is thus evident that if the degree of brake pipe leakage is small, passage '72 is uncovered by slide valve 19 only a slight amount, whereas if the leakage is great, passage '72 will be uncovered a greater amount in order to permit a greater quantity of fluid under pressure to flow to the brake pipe 16, or in other words, the degree of opening through passage '72, as governed by slide valve 19, will be varied in accordance with the degree of brake pipe leakage.

When an automatic application of the brakes is initiated and fluid under pressure is supplied from reservoir 104 to the locking piston chamber 30, the locking piston 29 operates plunger 24 to engage teeth 23 with teeth22 on slide valve 19, in the manner hereinbefore described. The

slide valve 19 is thus locked in the charging position it occupied when the brakes were released, and is thus permitted to continue supplying fluid under pressure to the brake pipe 16 to compen-,

reduce the brake pipe pressure and apply the under pressure to the "brake pipe at the same rate as leakage from the brake pipe tends to re duce the brake pipe pressure, such leakage is ineffective in aiding the brake pipe discharge valve in eiiecting a brake pipe reduction. Thus the amount or fluid under pressure that has to be vented from the brake pipe by'the'discha'rge valve 10 is substantially the same as if the brake pipe were leak-proof and thereforere uires the -same degree of time.

' When the first reduction is Completed and the control slide valve ie of the split reduction valve the'fluid at brake pipe pressure in diaphragm arrchamber 34- then shifts the slide valve 19' to lap position, in which passage 72 is lapped and the supply of fluid under pressure to the brake pipe is cut off. Leakage from the brake pipeis therefore permitted to aid in effecting the second stage of reduction in brakepipe pressure.

It will be noted that the brake pipe charging valve device functions to counteract'the leakage from the brake pipe only during the initial re-' duction 'andat the start of the second reduction operates to completelycut oh the fluid pressure supply to the brake pipe. This operation ensures 'a gatheringotthe slack in a train with brake pipe leakage with no greater intensity or shocks in'the' train than if there were no leak age, and after the slack is thus gathered, the

rate of brake pipe reduction is not so critical and is increased according to pipe leakage. g, e V e It is obvious from the above descriptionof operation, that substantially the same'interval of the degree of brake time will, elapse in-efiecting the first reduction in brake-pipe pressure on a train of a certain length, irrespective of the degree of brake pipe leakage, since the brake pipe charging valve de-' vice will automatically operate to supply fluid under pressure to the brake pipe duringlthe initial reduction to offset such leakage. In addition, however, the time between reductions will vary in proportion to the train length, since the time required to permit a certain reduction in brake pipe pressure depends upon the volume of brake pipe as determined by the length or" a train. The brake pipe charging valve device will, however, operate to compensate forbrake pipe leakage irrespective of train length.

It has heretofore been mentioned that the feed valve device 4 is adjusted to supply fluid at'a pressure in excess ofthatcarried in the brake This is essential in order to permit a handle 8 to turn rotary permitted 'to 'fiow past valve 19 and through passage 72 to the brake ,pipe 16. If the feed valve device 4 is adjusted to supply fluid at 70 pounds pressure, and the pressure desired in the brake pipe is 70 pounds, there will be only a'slightdifference in pressure in chamber 20,

, containing valve 19, and in the brake pipe, such difference being caused by the leakage. 7 Now as sume a first reduction in brake pipe pressure, of say 8 pounds, is effected. The (inference in pressure in valve chamber and the brake pipe is increased substantially eight times, or 800%', and acorrespondingly greater amount of fluid under pressure is supplied to the brake pipe at the end of the reduction, and a proportionately greater amount during the reduction, than was beingsupplie'd au the time the reduction was started. This is obviously undesirable in that it increases the amount of fluid under pressure to be vented from the brake pipe in effecting the first reduction and further increases the time required to effect the first reduction. To

prevent this undesirable result, a pressure is maintained in chamber 20 in excess of the brake pipe pressure carried, of for instance 10 pounds. Thus a 10 pound differential is provided to normally maintain the brake pipe charged against 1eakage,;while at the end of the first reduction of say 8 pounds, the differential is increased-to 18 pounds, or increased 80%, or only one tenth the increase effected if the feed valve 4 were adjusted to supply fluid at the pressure carried in the brake pipe. Thus the increase in rate of flow at the end of the first reduction is only slightly greater than at the start of said reduc-' tion, and for all practical purposes may be considered substantially the same. It is, however, obvious that as theadjustment of the feed valve device 4 is increased, the rate of flow to the brake pipe at the start and at the end of the brake pipe reduction will become more nearly thesame. I

'In orderto offset this increase in feed valve adjustment over brake pipe pressure carried, the spring is provided and is adapted to exert a pressure on the diaphragm 18 substantially equal to the dilferenc'e between feed valve ad- I justment and brake pipe pressure carried." After an automatic application of the brakes has been effected, as hereinbeiore described, if the magnet is again energized, the valve 56 will 'be'seated and fluid'pressure Will be built upin piston chamber 37 of the application valve device by flow from valvechamber 39 through the port 62in piston 36, and the fluid pressures on the opposite sides of piston 36 thus being permitted to equalize, the spring 40 will shift said piston and the slide valve 38 back to normal release position. 7 s

If at any time when the train control apparatus is' in release position, the operator desires to effect *an application of the brakes-byoperation of the brakezvalve device, he operates valve 7 to service'position. e v service position of the'rotary valve 7, feed valve passage 66 is disconnected from passage 68 and both passages are lapped, thereby cutting off the flow of fluid under pressure from the feed valve devices to the brake pipe charging valve slide valve chamber 20, which renders the brake pipe charging valve device inoperative to supply fluid under pressure to the brake pipe. At the sametime as the supply of fluid under pressure is cut off to the brake pipe, the equalizing resorvoir 13 and equalizing piston chamber 11 are opened. to the atmosphere through passage l2, cavity 75 in the application slide valve 38, passage 74 and atmospheric passage 103, thereby permitting the pressure of fluid in chamber 11 to reduce. The equalizing piston 9 then operates the brake pipe discharge valve 10 to effect a reduction in the pressure in brake pipe 16 in the usual manner.

To release an application of the brakes eflected by operation of the brake valve device, the brake valve rotary valve is turned to release position in Which the brake pipe is recharged with fluid. under pressure in the same manner as hereinbefore described.

While one illustrative embodiment of the invention has been described in detail, it is not my intention to limit its scope to that embodiment or otherwise than by the terms of the appended claims.

Having now described my invention, What I claim as new and desire to secure by Letters Patent, is:

1. In a fluid pressure brake, the combination with a brake pipe, of a valve mechanism for effecting successive reductions in the pressure of fluid in said brake pipe, valve means operative when said valve mechanism is effecting the initial reduction in brake pipe pressure for supplying fluid under pressure to said brake pipe to oiiset leakage from said brake pipe, and means operative, after the initial reduction in brake pipe pressure is effected by said valve mechanism, for rendering said valve means inoperative to supply fluid under pressure to said brake pipe.

2. In a fluid pressure brake, the combination with a brake pipe, of valve mechanism subject to brake pipe pressure and having a charging position for normally supplying fluid under pressure to said brake pipe at a rate corresponding to the rate of leakage of fluid under pressure fromsaid brake pipe, a split reduction valve device for effecting successive reductions in brake pipe pressure to apply the brakesin two stages, means operated during the initial brake pipe reduction to lock said. valve mechanism in charging position and operative after the initial brake pipe reduction is completed to unlock said valve mechanism and permit same to be operated by brake pipe pressure to cut off the supply of fluid under pressure to said brake pipe.

3. In a fluid pressure brake, the combination with a brake pipe, of valve mechanism for maintaining the pressure of fluid in said brake pipe against leakage by supplying fluid under pressure to said brake pipe at a rate corresponding to the rate of leakage of fluid under pressure from said brake pipe, a brake pipe discharge valve for venting fluid under pressure from said brake pipe to efiect an application or" the brakes, means auto-- matically operative, if traflic conditions become unfavorable, for locking said valve mechanism in its maintaining position, and. at the same time for causing said brake pipe discharge valve to operate to vent fluid under pressure from said brake pipe,

a valve device for limiting the degree of brake in brake pipe pressure, valve means controlled by said valve mechanism for supplying fluid under pressure to said brake pipe during the first reduction in brake pipe pressure at a rate .corresponding to the rate of leakage of fluid under pressure from said brake pipe, and means operative after the first reduction is completed for rendering said valve means inoperative to supply fluid under pressure to said brake pipe.

5. In a fluid pressure brake, the combination with a brake pipe, of valve mechanism automatically operative to effect successive reductions in brake pipe pressure, and means controlled by said valve mechanism for supplying fluid under pressure to said brake pipe during the first reduction in brake pipe pressure at a rate corresponding to the rate of leakage of fluid under pressure from said brake pipe, and. operative after the first reduction is completed to cut oif the supply of fluid under pressure to said brake pipe, said means comprising a \valve, pressure sensitive means, for operating said valve, and fluid pressure operated means for locking said valve in charging position during the first reduction.

6. In a fluid pressure brake, the combination with a brake pipe, of valve mechanism automatically operative to effect successive reductions in brake pipe pressure, and means controlled by said valve mechanism for supplying fluid under pressure to said brake pipe during the first reduction in brake pipe pressure at a rate corresponding to the rate of leakage of fluid under pressure from said brake pipe, and operative after the first reduction is completed to cut off the supply of fluid under pressure to said brake pipe, said means com-prising a slide valve, a pluralityof flexible diaphragms for operating said slide valve, and a piston operated plunger tor engaging said slide Valve during the first reduction for locking same in charging position.

7. In a fluid pressure brake, the combination with a main reservoir and a brake pipe, of a feed valve device for reducing the pressure of fluid from saidmain reservoir to a pressure greater than carried in said brakepipe, a valve device controlled by the pressure of fluid insaid brake pipe and the pressure of a spring for supplying fluid under pressure from saidfeed.- valve device to said brake pipe and. operativebythe pressure of fluid in said brake pipe to out off the supply of; fluid under pressure to said brake pipe after the first stage of a two stage reduction in brake pipev pressure is completed.

8. In a fluid pressure brake, the combination with; a brake pipe, of a valve device operative normally to supply fluid under pressure to said brake pipe and also operative to cut off thesupply of fluid: under pressure to said brakepipe after the first stage of a two stage reduction inbrake pipe pressure iscompleted, a mainreservoir, and a feed valve device for supplying fluid from said main reservoir to said valve device at a pressure higher than carried in. said brake pipe,said. valve device being normally controlled by-the opposing pressures of fluid at the pressure supplied by said feed valve device in one chamber, and. brake pipe pressure and the pressure of a spring in another chamber. 1

9. In a fluid pressurev brake, the combination with. a brake pipe, of a valve device-for supplying fluid under pressure to said brake pipe. during a brake pipe reduction to compensate for leakage of fluid under pressure from said brake pipe, a main reservoir, and a feed valve device for supplying fluid under pressure from said mainresrv'oi'r to said valve device at a pressure adapted to provide a substantially constant flow through said valve device to the brake pipe throughout the range of said reduction in brake pipe pressure.

10. In a fluid pressure brake, the combination with a brake pipe, of charging means for charging the brake pipe at a rate to compensate for leakage from the brake pipe, means for effecting a reduction in brake pipe pressure, and means operating upon a reduction in brake pipe pressure for locking said charging means in its charging position.

11. In a fiuid pressure brake, the combination with a brake pipe, of charging means for charging the brake pipe at'a rate to compensate for leakage from the brake pipe, means for effecting a first reduction in brake pipe pressure and then a second reduction in brake pipe pressure, and means operated upon effecting the first reduction in brake pipe pressure for maintaining said charging means in its charging position.

12. In a fluid pressure brake, the combination with a brake pipe, of charging means for chargwith a brake pipe, of charging means for charg- 7 1 ing the brake pipe at a rate to compensate for leakage from the brake pipe, means for efiecting a first reduction in brake pipe pressure and then a second reduction in brake pipe pressure, means operated upon effecting the first reduction in brake pipe pressure for looking said charging means in its charging position, and means operated upon efiecting the second reduction in brake pipe pressure for releasing said charging means.

UNCAS A..WHITAKER. 

